1. Technical Field
The disclosure generally relates to light guide plates and backlight sources, and particularly to a light guide plate with Fresnel lenses and V-shaped grooves, and a backlight source using the light guide plate.
2. Description of Related Art
A typical liquid crystal display (LCD) device generally includes a backlight module and a liquid crystal panel. The backlight module includes a light guide plate and a light source. The backlight module is used to provide a surface light source for illuminating the liquid crystal panel. In operation, the light guide plate converts light beams from the light source into surface light beams, and directs the surface light beams to the liquid crystal panel.
Referring to FIG. 3, a typical backlight module 10 for a liquid crystal display device is shown. The backlight module 10 includes a light guide plate 11 and a plurality of light sources 12. The guide plate 11 generally is rectangular, and includes an light incident surface 110, and an light emitting surface 112 adjoining the light incident surface 110. The light sources 12 are arranged adjacent to the light incident surface 110. In operation, light beams emitted from the light sources 12 is projected to the light guide plate 11. The light beams is then guided in the light guide plate 11 and projected from the light emitting surface 112 of the light guide plate 11.
Light emitting diodes (LEDs) are currently used extensively as light sources 12 of the backlight module 10 due to their high luminous efficiency, low power consumption and long life span. The LEDs 13 are generally spaced from one another. Each LED 13 has a limited radiating range. For example, a single LED 13 may emit light beams with an emitting angle in a range from about 30 degrees to about 130 degrees. In such case, a plurality of bright bands 13, which have larger luminance and a plurality of dark bands 15, which have less luminance may be formed alternately on the light emitting surface 112. The light guide plate 11 may not evenly distribute the light beams over an entire light emitting surface 112 thereof.
Therefore, what is needed is a light guide plate and a backlight source using same, which provides uniform output light thereby overcoming the described limitations.